Bitmap conversion

Detailed Description

The i2v and v2i family of functions convert between a bitmap and a bit index.

A bitmap is simply an integer with certain bits being 1 (enabled) and 0 (disabled).

These functions only return usable results if exactly one bit is enabled.

Bit index to bitmap
The resulting bitmask is a simple arithmetic left shift of 1 index times.
Bitmap to bit index
The resulting bit index is asimple arithmetic right shift until the map is empty.

These functions are mainly used by the flist family of functions.

Functions

uint32_t i2v32 (int index)

convert bit index to 32 bit value

uint64_t i2v64 (int index)

convert bit index to 64 bit value

int v2i32 (uint32_t val)

convert 32 bit value to bit index

int v2i64 (uint64_t val)

convert 64 bit value to bit index

Function Documentation

uint32_t i2v32 ( int index )

convert bit index to 32 bit value

Parameters:

[in] index bit index (0-31)

Returns:: 32 bit value

Definition at line 19 of file i2v32.c.

00020 {
00021         if (index < 0 || index > 31)
00022                 return 0;
00023 
00024         return (1UL << index);
00025 }

uint64_t i2v64 ( int index )

convert bit index to 64 bit value

Parameters:

[in] index bit index (0-63)

Returns:: 64 bit value

Definition at line 19 of file i2v64.c.

00020 {
00021         if (index < 0 || index > 63)
00022                 return 0;
00023 
00024         return (1ULL << index);
00025 }

int v2i32 ( uint32_t val )

convert 32 bit value to bit index

Parameters:

[in] val 32 bit value

Returns:: bit index (0-31)

Definition at line 19 of file v2i32.c.

00020 {
00021         int index = 0;
00022 
00023         if (val == 0)
00024                 return -1;
00025 
00026         while ((val = val >> 1))
00027                 index++;
00028 
00029         return index;
00030 }

int v2i64 ( uint64_t val )

convert 64 bit value to bit index

Parameters:

[in] val 64 bit value

Returns:: bit index (0-63)

Definition at line 19 of file v2i64.c.

00020 {
00021         int index = 0;
00022 
00023         if (val == 0)
00024                 return -1;
00025 
00026         while ((val = val >> 1))
00027                 index++;
00028 
00029         return index;
00030 }

Generated on Tue Jun 19 20:27:41 2007 for lucid by

1.5.2


Functions
uint32_t	i2v32 (int index)
	convert bit index to 32 bit value
uint64_t	i2v64 (int index)
	convert bit index to 64 bit value
int	v2i32 (uint32_t val)
	convert 32 bit value to bit index
int	v2i64 (uint64_t val)
	convert 64 bit value to bit index